1. Field of the Invention
This invention relates to a liquid crystal display, and more particularly to a thin film transistor substrate and a fabricating method thereof that are adaptive for simplifying a process.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) controls light transmittance of a liquid crystal having a dielectric anisotropy using an electric field to thereby display a picture. To this end, the LCD includes a liquid crystal display panel for displaying a picture by a liquid crystal cell matrix, and a driving circuit for driving the liquid crystal display panel.
Referring to FIG. 1, a related art liquid crystal display panel is comprised of a color filter substrate 10 and a thin film transistor substrate 20 that are joined to each other with having a liquid crystal 24 therebetween.
The color filter substrate 10 includes a black matrix 4, a color filter 6 and a common electrode 8 that are sequentially provided on an upper glass substrate 2. The black matrix 4 is provided in a matrix type on the upper glass substrate 2. The black matrix 4 divides an area of the upper glass substrate 2 into a plurality of cell areas to be provided with the color filter 6, and prevents a light interference between adjacent cells and an external light reflection. The color filter 6 is provided at the cell area divided by the black matrix 4 in such a manner to be divided into red(R), green(G) and blue(B) ones, thereby transmitting red, green and blue lights. The common electrode 8 is formed from a transparent conductive layer entirely coated onto the color filter 6, and supplies a common voltage Vcom that serves as a reference voltage upon driving of the liquid crystal 24. Further, an over-coated layer (not illustrated) for smoothing the color filter 6 may be provided between the color filter 6 and the common electrode 8.
The thin film transistor substrate 20 includes a thin film transistor 18 and a pixel electrode 22 provided for each cell area defined by an crossing between a gate line 14 and a data line 16 at a lower glass substrate 12. The thin film transistor 18 applies a data signal from the data line 16 to the pixel electrode 22 in response to a gate signal from the gate line 14. The pixel electrode 22 formed from a transparent conductive layer supplies a data signal from the thin film transistor 18 to drive the liquid crystal 24.
The liquid crystal 24 having a dielectric anisotropy is rotated in accordance with an electric field formed by a data signal from the pixel electrode 22 and a common voltage Vcom from the common electrode 8 to control light transmittance, thereby implementing a gray scale level.
Further, the liquid crystal display panel includes a spacer (not illustrated) for constantly keeping a cell gap between the color filter substrate 10 and the thin film transistor substrate 20.
In such a liquid crystal display panel, the color filter substrate 10 and the thin film transistor substrate 20 are formed by a plurality of mask processes. Herein, one mask process includes a lot of processes such as thin film deposition (coating), cleaning, photolithography, etching, photo-resist stripping and inspection processes, etc.
Particularly, because the thin film transistor substrate includes the semiconductor process and requires a plurality of mask processes, it has a complicated fabricating process which is major factor in the increased manufacturing cost of liquid crystal display panels. Therefore, the thin film transistor substrate has been developed to reduce the number of mask process.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.